Various acrylic fiber polymer precursors have been utilized in the production of acrylic fibers for use in outdoor applications, such as in awnings and other outdoor textiles due to certain desirable physical properties (e.g., decay resistance, UV stability weather fastness, etc.). For example, U. S. Pat. No. 4,265,970 describes an acrylic fiber that was utilized in acrylic fabric for outdoor textiles. This fiber is formed from an acrylic fiber polymer precursor having less than 93 wt. % acrylonitrile monomer and 7 wt. % or more vinyl acetate (VA). However, the fabric produced from such fibers possesses inadequate hot-wet properties such as elongation.
Large amounts of vinyl monomers (e.g., above 7 wt. %), have been included in polymer formulations for the purpose of providing the fiber with flame retardency, additional dyesites, or increased hydrophilility. However, vinyl monomer amounts below 7 wt. % have not been utilized due to problems in spinning the resulting polymer. Lower amounts of vinyl monomers have not been used due to solutioning difficulties in dimethylacetamide such as filtration prior to spinning of the solutioned polymer, poor fiber color from elevated solutioning temperatures, and low standard fiber elongation under ambient conditions.
In spite of the desirable physical properties manifested by acrylonitrile containing fibers, there are a number of difficulties encountered during the processing of fabrics made therefrom, and still provide adequate hot-wet properties. Various means have been employed in the art to improve the tensile properties of such fibers under hot-wet conditions. A number of means involve incorporating various chemical agents to modify the structural arrangement of the polymer itself. Several methods have been employed which physically modify the fiber structure. These methods and combinations thereof have met with limited success. During processing of fabrics containing polyacrylonitrile where such fabrics are exposed to heat and water or steam, deformation owing in part to a plasticity of such polyacrylonitrile materials is frequently observed. Furthermore, wrinkling or overstretching when a woven or knitted fabric thereof is subjected to tension is often exhibited. Other desirable properties for outdoor textiles include high abrasion resistance and low lint generation.
Dolan.RTM. T-65 is an outdoor textile material manufactured by Courtaulds Fibers, Inc. that is made almost entirely from a polyacrylonitrile (PAN) homopolymer (including less than about 0.8 wt. % methyl acrylate). The Dolan.RTM. T-65 acrylic fabric was made in an attempt to improve upon the hot-wet properties of previous acrylic fabrics. However, it is not possible to use a polymer, such as in the Dolan 65, which is nearly a homopolymer in all spinning solvents and provide adequate hot-wet properties. For example, using certain spinning solvents such as dimethylacetamide, to spin acrylic fiber requires a high dissolution temperature of approximately 120.degree. C. or higher. When spinning acrylonitrile under normal residence times in solution at this elevated temperature, white base polymer color in the resulting fiber cannot be achieved.
Accordingly, there is a need for an acrylic fiber polymer precursor composition that may be economically and easily processed into acrylic fiber, which has desirable appearance, and improved hot-wet and abrasion properties.